1) Field of the Invention
The present invention is directed to synthetic muscles and methods for actuating synthetic muscles.
2) Description of Prior Art
Synthetic muscle has been developed that uses inflatable balloons to produce a tensile force from a positive pressurization. Mechanical supply and ducting is used to provide the required pressurization. However, the mechanical supply and ducting that is currently used is limited in several respects. First, the required piping system can become very complex if a multitude of small fibers is needed for a particular application. Second, moving fluid from a central supply to small individual cells via small ductwork is prone to mechanical losses. Third, finding an optimum balance between time required to move fluid from a central supply to the cells, supply pressure and mechanical integrity of the ducting system could be problematic. For example, large ducting and cell volumes can lead to lengthy times required to fill the cells and consequently limit the effective system actuation rates.
To optimize rate of actuation, it is desirable to minimize the cell volume and to maximize the area through which fluid is forced into the cell. Ideally, a fully closed cell that is inflated through some mass transfer process that takes place through the cell boundary would lead to a maximum cell response rate. With such a system, the transfer rate would scale with the cell surface area, i.e., square of diameter, and the fill-volume of the cell would scale with the cube of the diameter. The time required to fill the cell is the volume divided by the rate, which scales as the diameter of the cell. It follows that as the dimensions of the individual cells is reduced, the time required to fill the cell is proportionately reduced, i.e. very small cells fill very rapidly.
To make use of this aspect of miniaturization, a method is needed to move the working fluid through the cell walls.